This invention relates in general to wrapping machines and deals more particularly with an improved stretch wrapping machine for packaging articles, such as trays of produce, poultry, meat and the like in stretchable wrapping material such as plastic film. Wrapping machines of the aforedescribed general type have been heretofore available and typical wrapping machines of the type with which the present invention is concerned are illustrated and described in U.S. Pat. Nos. 3,662,513 to Fabbri, issued May 16, 1972 and 3,977,158 to Jennings et al, issued Aug. 31, 1976. Such stretch wrapping machines generally utilize a matrix plate which has an opening of fixed size generally corresponding to the article to be wrapped. During the stretching phase of the wrapping cycle, an article to be wrapped is pushed upwardly against a stretchable wrapper and through the opening in the matrix plate while opposing edges of the wrapper are held fast, so that the wrapper is stretched over the article and pulled inwardly against its sides. Such an arrangement is quite satisfactory for use in a machine for long run production when articles to be wrapped do not vary significantly in size and shape. However, when such a machine is used in short run production to wrap articles which vary significantly in character it is necessary to remove the matrix plate at the end of each production run and replace it with another matrix plate corresponding to the next article to be wrapped. Such machine setup operations require a skilled mechanic and result in substantial machine downtime. The present invention is concerned with the aforedescribed problem.
It is the general aim of the present invention to provide an improved stretch wrapping machine which may be rapidly and accurately adjusted by a person of ordinary skill, such as a machine operator, and which may be adjusted to wrap articles in a wide range of sizes without removing or replacing machine parts.